| name | polymarket |
| description | Query Polymarket prediction market data — search markets, get prices, orderbooks, and price history. Read-only via public REST APIs, no API key needed. |
| version | 1.0.0 |
| author | Hermes Agent + Teknium |
| tags | ["polymarket","prediction-markets","market-data","trading"] |
Polymarket — Prediction Market Data
Query prediction market data from Polymarket using their public REST APIs.
All endpoints are read-only and require zero authentication.
See references/api-endpoints.md for the full endpoint reference with curl examples.
When to Use
- User asks about prediction markets, betting odds, or event probabilities
- User wants to know "what are the odds of X happening?"
- User asks about Polymarket specifically
- User wants market prices, orderbook data, or price history
- User asks to monitor or track prediction market movements
Key Concepts
- Events contain one or more Markets (1:many relationship)
- Markets are binary outcomes with Yes/No prices between 0.00 and 1.00
- Prices ARE probabilities: price 0.65 means the market thinks 65% likely
outcomePrices field: JSON-encoded array like ["0.80", "0.20"]clobTokenIds field: JSON-encoded array of two token IDs [Yes, No] for price/book queriesconditionId field: hex string used for price history queries- Volume is in USDC (US dollars)
Three Public APIs
- Gamma API at
gamma-api.polymarket.com — Discovery, search, browsing
- CLOB API at
clob.polymarket.com — Real-time prices, orderbooks, history
- Data API at
data-api.polymarket.com — Trades, open interest
Typical Workflow
When a user asks about prediction market odds:
- Search using the Gamma API public-search endpoint with their query
- Parse the response — extract events and their nested markets
- Present market question, current prices as percentages, and volume
- Deep dive if asked — use clobTokenIds for orderbook, conditionId for history
Presenting Results
Format prices as percentages for readability:
- outcomePrices
["0.652", "0.348"] becomes "Yes: 65.2%, No: 34.8%"
- Always show the market question and probability
- Include volume when available
Example: "Will X happen?" — 65.2% Yes ($1.2M volume)
Parsing Double-Encoded Fields
The Gamma API returns outcomePrices, outcomes, and clobTokenIds as JSON strings
inside JSON responses (double-encoded). When processing with Python, parse them with
json.loads(market['outcomePrices']) to get the actual array.
Rate Limits
Generous — unlikely to hit for normal usage:
- Gamma: 4,000 requests per 10 seconds (general)
- CLOB: 9,000 requests per 10 seconds (general)
- Data: 1,000 requests per 10 seconds (general)
Limitations
- This skill is read-only — it does not support placing trades
- Trading requires wallet-based crypto authentication (EIP-712 signatures)
- Some new markets may have empty price history
- Geographic restrictions apply to trading but read-only data is globally accessible
